This paper reviews the key conceptual models used in research on teacher development, in particular examining the strengths and limitations of expertise and career development models. The expertise development of a teacher is generally classified into several stages; novice, beginner, competent, skilled, and expert, while teacher career development models encompass; pre-service, recruitment, induction, professional development and lifelong education. Conventional teacher development models were conceptualised as a linear progression, however, recently, there has been an emergence of non-linear models, with concepts which could improve understanding of teacher development. Overall, there is a lack of models which connect expertise and career development of teachers. Yet there are several concepts in each type of model that, once considered in depth, could steer future empirical study of teacher development in a more meaningful direction.